The present invention relates to a metal laminate gasket for sealing around a hole by means of a bead and a sealing groove for receiving the bead therein.
In a metal gasket, it is common to form a bead on a metal plate around a hole to be sealed. The bead projects outwardly from the metal plate and includes a top portion and two base portions at the bottom of the bead. When the bead with the top portion and the base portions is tightened between two engine parts, the bead is compressed by the engine parts, so that the bead is flattened and generally forms a plurality of corrugated beads to tightly seal around the hole.
In the corrugated beads, strong sealing forces are formed at portions corresponding to the top portion and two base portions. Generally, the sealing force at the top portion acts in the direction that the bead projects, and the sealing forces at the base portions act in the direction opposite to the sealing force of the top portion. Accordingly, the bead can seal widely at the base portions rather than at the top portion.
In view of the above characteristics of the bead, Japanese Utility Model Publication (KOKAI) No. 62-181756 was proposed, wherein a gasket is formed of an inner plate having two grooves and two outer plates having beads respectively. Top portions of the beads are situated in the grooves of the inner plate so that base portions orient outwardly.
In the above Japanese publication, although the base portions seal between the gasket and the engine parts, the top portions are simply located in the grooves. Since large forces are applied to the top portions when the gasket is tightened, the top portions of the two beads must face against each other through the inner plate. Otherwise, the inner plate may be bent by the force supplied to the top portions of the beads.
In view of the disadvantages of the above prior art, the present invention has been made.
Accordingly, one object of the invention is to provide a metal laminate gasket, which has wide and strong sealing areas without concentrating sealing force at one point.
Another object of the invention is to provide a metal laminate gasket as stated above, which is relatively thin while forming grooves and beads.
A further object of the invention is to provide a metal laminate gasket as stated above, wherein surface pressures can be regulated easily.
A still further object of the invention is to provide a metal laminate gasket as stated above, which can be easily and economically manufactured.
Further objects and advantages of the invention will be apparent from the following description of the invention.